Various salts of the acids of phosphoric acid, usually orthophosphoric acid or pyrophosphoric acid are commonly employed as the acid factor in combination with a carbonate factor in leavening systems. Calcium, aluminum and sodium salts, exhibiting different reaction profiles, find use as leavening acids in different applications. Sodium, aluminum and calcium salts have been widely used as the acid factor in leavening systems.
The use of sodium acid pyrophosphate as an acid factor in bakery leavening is known but an undesirable flavor has been observed. Mixing a calcium acid phosphate salt with sodium acid pyrophosphate (SAPP) has been found to reduce or eliminate the taste and also control the evolution of gas after mixing the baking ingredients. In U.S. Pat. No. 1,834,747 to Stokes et al. there is described baking powder formulas which contain the usual sodium bicarbonate together with alkaline earth metal phosphates such as monocalcium phosphate in admixture with sodium acid pyrophosphate. It is reported that the mixture results in a slowing of the evolution of carbon dioxide as compared to sodium acid pyrophosphate alone thereby allowing a more desirable reaction profile. With variation in the amounts of the various salts it is reported that the evolution of gas during leavening can be controlled to provide varied reaction profiles depending upon the requirements.
Baking powders contain as essential ingredients an acid-reacting material and sodium bicarbonate, with or without a filler. The acid-reacting materials customarily used are alum and acid salts of phosphoric acid, pyrophosphoric acid, or combinations of these materials. See U.S. Pat. Nos. 2,630,372; 3,052,549; and 3,501,314.
Most modern chemical leavening compositions used in baked goods are of the double action type, i.e. they contain a fast-acting acid to release sufficient carbon dioxide quickly enough to provide nucleation of the batter or dough and a good lift during the early stages of baking. A slower or heat activated acid releases additional carbon dioxide during baking before the starch coagulation temperature is reached, maximizing expansion and during the remainder of the baking period to maintain the expansion. The quickly released gas acts before structure has set and is essential to best texture and maximum volume in the finished baked goods. The slowly released gas is essential to maintenance of maximum volume with minimum shrinkage after the baked goods structure has set, i.e., during the middle and last stages of baking.
Previously, the rate of reaction of alkali metal pyrophosphate leavening acids has been modified by blending such acids with an oxide or hydroxide of magnesium. It is reported that such magnesium compounds differ from the previously known reaction modifiers such as calcium compounds in that the magnesium compounds were essentially insoluble. See U.S. Pat. No. 4,741,917 to Lauck et al. According to this patent, magnesium oxide having a particle size of from 1 to 50 microns and a loss on drying of less than 10% is blended with such standard leavening acids as sodium acid pyrophosphate (SAPP). Weight ratios of SAPP to magnesium oxide ranges from 10:1 to 1,000:1. Such modified leavening acids are said to be particularly effective in canned, refrigerated biscuits where low gas generation during mixing, and canning is important. Additional steps of co-milling the SAPP and calcium hydroxide or magnesium oxide followed by heat treating the co-milled product is said to further reduce the rate of reaction of the SAPP at room temperature. See U.S. Pat. No. 4,804,553 to Tieckelmann. The co-milled mixture is thermally treated at 200.degree. C. to 250.degree. C. with or without the presence of moisture in the form of steam. Such treatment is said to reduce the reaction rate of SAPP by as much as 50%, rendering the leavening acid highly desirable for use in canned, refrigerated dough. The SAPP, modified with magnesium oxide, is not a heat activated leavening acid as it still is capable of releasing a large portion of the available carbon dioxide at room temperature if sufficient time is provided.
Leavening acids are selected based upon their profile of carbon dioxide release as a function of time. There are acids which react rapidly upon mixing and release the carbon dioxide while the dough or batter is in the mixing bowl. The fast reacting acids include monocalcium phosphate, fumaric acid, citric acid, adipic acid, potassium tartrate, monoammonium phosphate, and monosodium phosphate. Other acids provide time delayed release of carbon dioxide such as sodium acid pyrophosphate, calcium acid pyrophosphate, glucono-delta-lactone and fumaric acid. Some are activated by temperature. Heat activated leavening acids are known. Those which are considered heat activated are sodium aluminum phosphates, dicalcium phosphate dihydrate, aluminum sulfate and sodium aluminum sulfate. All leavening acid reactivities are increased in rate with the exposure to heat. The heat activated acids, however, do not react significantly at room temperature. Alternatives to the sodium heat activated salts have been attempted but there is usually a disadvantage associated with them. For example, the dicalcium phosphate dihydrate reacts too slowly to provide leavening in the early phases of baking. Other calcium salts have not demonstrated heat activation. The dimagnesium phosphate trihydrate does provide leavening on its own; however, the profile of release is not optimum for use alone.
There is needed a suitable alternative to the sodium heat activated leavening salts.